1. Field of the Invention
The present invention relates to a printing control apparatus and a printing control method, and more particularly to a printing processing of an image including a copy-forgery-inhibited pattern image for checking the usage of a copying material in a system configured to include an information processing unit such as a personal computer and a printing apparatus such as a printer.
2. Description of the Related Art
Conventionally, in order to prohibit copying a ledger sheet, a resident card, and the like, or restrain people from doing so, papers on which special printing is given, papers called anti-counterfeit paper have been used. The anti-counterfeit paper is a paper in which characters or the like such as “COPY” is embedded to be hard to recognized by a human eye when the paper is in a state of an original and to show up on the copied paper when the original is copied using a copying machine or the like. Thereby, people can visually distinguish a print sheet as the original from the duplicate made by copying the original, easily. The use of this anti-counterfeit paper as an original causes those who copy the original to hesitate to use duplicated papers. Moreover, the anti-counterfeit paper gives a mental restraint effect of inhibiting an act of copying itself. The reason why characters in the original of the anti-counterfeit paper needs to be hard for people to recognize is to enable people to distinguish between the original and the duplicate definitely. If characters such as “COPY” is recognizable to such an extent that people can clearly recognize it even in the original, there may occur the possibility that people recognize it as the duplicate and such paper does not make a sense as the anti-counterfeit paper. Wicker (U.S. Pat. No. 5,788,285) and Mowry et al. (U.S. Pat. No. 6,000,728) disclose arts for manufacturing such an anti-counterfeiting paper.
However, since the anti-counterfeit paper like this is made by fully employing a special printing technology, it comes with a problem of high cost compared to normal papers. Moreover, the anti-counterfeit paper can make only characters that are set at the time of manufacturing show up. Therefore, an application of the anti-counterfeit paper and characters being set are limited. That is, the conventional anti-counterfeit paper lacks flexibility regarding applications because of a matter on its manufacture.
On the other hand, as various contents are being digitized, the contents of ledger sheets, a resident card, or the like are being transformed into digital data similarly. However, digitization for handling of these ledger sheets and resident cards, such as use of these documents, is still in a transition phase. Consequently, the contents of digital data formed using a computer is likely to be outputted on papers with a printer or the like for subsequent use.
Under such circumstances, significant improvement in printer performance has been achieved in recent years, and this is one of cause for a technology, which makes it possible to print out a paper on demand that has the same effect as the conventional anti-counterfeit paper using a computer and a printer, to attract an attention. Japanese Patent Application Laid-open No. 2001-197297 and Japanese Patent Application Laid-open No. 2001-238075 disclose technologies whereby, when contests data formed using a computer is printed out with a printer, an image called copy-forgery-inhibited pattern image (a copy-forgery-inhibited pattern) is also outputted with superposed on the background of the contents data. The copy-forgery-inhibited pattern image is an image that is recognized only as a simple pattern or a mere background color in the original (a printed matter outputted by a printer) to the human eye, but, when it is copied, will show up as predetermined characters or the like in the duplicate. Thereby, the same restraint effect as the anti-counterfeit paper can be given to those who copied.
In the case that the contents are printed out together with a copy-forgery-inhibited pattern image generated by a computer, being superposed thereon, naturally a normal printing paper or the like can be used. Therefore, this technology has an advantage in terms of cost in comparison with the technology using the anti-counterfeit paper. Moreover, the copy-forgery-inhibited pattern image can be generated when the contents are outputted by printing. Thereby, characters or the like that will be made visible at the time of copying can be set freely. Further more, there is also an advantage that dynamic information, such as a user name who executed printing and printout time and date, can be made to show up as the characters.
The copy-forgery-inhibited pattern image, as discussed above, is one that, when being duplicated, visualizes a predetermined character or the like that could not be recognized before duplication, therefore restrains people from using the duplicate, and realizes an effect of enabling people to visually identify what the people sees to be the duplicate, in other words, not to be the original easily. In order to realize this effect, the copy-forgery-inhibited pattern image is basically composed of two areas: an area which remains (shows up) in the duplicate when being copied, and an area which disappears in the duplicate or becomes too light-colored to recognize compared to the image remaining area. These two areas, as being printed, are of almost the same density, and therefore no one can recognize that characters etc., such as “COPY” that will become visible by duplication are hidden (embedded) therein at first sight, in a macroscopic sense. However, in a microscopic sense, for example, in a level of printed dots, these two areas have different characteristics, respectively, as will be shown below.
Hereafter, an image that will show up by duplication is called a “latent image” and an image that will disappear or become light-colored is called a “background” for convenience. The copy-forgery-inhibited pattern image is basically composed of the latent image and the background image. Incidentally, there may be a case where the latent image is called a foreground as a term related to a user interface.
In addition, copy-forgery-inhibited pattern may be called tint block.
Note that tint block printing is not limited to the above-mentioned composition, and the copy-forgery-inhibited pattern image may be composed in such a way that characters, such as a “COPY”, a logo, or a pattern will be rendered (will become visible) as an recognizable image to the human eye in the duplicate. That is, even if the characters “COPY” are rendered as outlined characters in the duplicate, it will achieve its object as tint block printing. In this case, needless to say, the characters of “COPY” are generated as a background image.
Now, in the case of dot printers, such as of electro-photographic and ink jet systems, an area which will remain in the duplicate (latent image section or foreground section) consists of sets of concentrated dot masses. The area which will disappear or be reproduced with thinner density (background section) than the image density in the area which will remain consists of sets of dispersed dots. Moreover, in a state where the copy-forgery-inhibited pattern image is printed, the density of the whole copy-forgery-inhibited pattern image can be made almost uniform by setting the images in such a way as to have almost equal density in respective areas.
FIG. 1 is a view showing these two areas. As shown in this figure, the copy-forgery-inhibited pattern image is composed of both the background section in which dots are arranged dispersedly and the latent image section in which concentrated dot masses are arranged. These two areas can be generated by mutually different half tone dot processing and dither processing. In the case where the copy-forgery-inhibited pattern image is generated using the half tone dot processing, half tone dot processing with a small number of lines is suited for the latent image and that with a large number of lines is suited for the background section. In the case where the copy-forgery-inhibited pattern image is generated using dither processing, dither processing using a dot concentration type dither matrix is suitable for the latent image section, and dither processing using a dot dispersion type dither matrix is suitable for the background section.
The copying machine generally has critical points in reproducing capability that depends on input resolution of reading fine dots of a manuscript and output resolution of reproducing fine dots. In the case where the dot in the background section of the copy-forgery-inhibited pattern image is formed smaller than the critical point of dots that the copying machine can reproduce and the dot masses in the latent image section thereof are formed larger than the critical point, an image composed of larger dot masses of the copy-forgery-inhibited pattern image is reproduced and an image composed of smaller dots is not reproduced, in the duplicate by copying. As a result, the latent image will be made visible. Moreover, even in the case where dispersed small dots are not completely disappeared by copying, i.e., in the case where the density of the background section is low compared to that of concentrated dot masses, relatively the latent image can be recognized more markedly.
FIGS. 2A and 2B are views showing visualization of a latent image. FIG. 2A is a view corresponding to a state where the copy-forgery-inhibited pattern image is printed. FIG. 2B is view corresponding to a duplicate obtained when FIG. 2A was copied by a copying machine. From FIG. 2A and FIG. 2B, it may be understood that the latent image by the concentrated dot masses will show up and the background by the dispersed dots will disappear.
Generally, a color printer has a plurality of color processing modes such as a full-color printing mode and a black-and-white printing mode. In recent years, however, it has become a common practice to employ a color processing mode automatic switching function for cost reduction such as toner savings. The color processing mode automatic switching function carries out such processing as printing a page in the black-and-white mode even when the full-color printing is designated, if the page to be printed consists of only black-and-white data. The function is disclosed in Japanese Patent Application Laid-open No. 5-019993 (1993), for example. In addition, in a printing-time color processing mode, the charge processing for printing job on a page by page basis has been operating.
FIG. 3 shows an example of a user interface of a color processing mode designating method. As illustrated in a menu 5101 of FIG. 3, the present example provides three types of color processing modes: a “full-color/monochrome automatic switching” mode for switching the color mode in accordance with the contents of the output page; a “full-color” mode for always printing in the color mode; and a “monochrome” mode for always printing in the monochrome mode.
As for the method of designating the color mode to the printer, it is common to add a job command as shown below to the initial position of the printing data. Commands for making the automatic, color and monochrome commands to the printer are as follows.
JL SET COLOR-MODE=AUTO
JL SET COLOR-MODE=COLOR
JL SET COLOR-MODE=MONOCHROME
In the tint block (a copy-forgery-inhibited pattern) printing, however, when the monochrome mode printing is carried out under such conditions as the color tint block is set, and if the tint block color is output as it is, the device or driver performs the color/monochrome conversion. In this case, a copy-forgery-inhibited pattern image may be converted to image data which represents black impromptu by mixing cyan, magenta, yellow and the like with desired ratio rather than using only black ink or toner. Also, even when using black ink and toner, a copy-forgery-inhibited pattern image may not be converted to a optimized concentration as a monochrome copy-forgery-inhibited pattern image. Thus, the copy-forgery-inhibited pattern image cannot become the desired image and thickness because of the effect of dither process and the like, thereby resulting in an image that cannot make the full effect of the tint block printing.